With the development of the battery technology, electric tools are gradually replacing engine tools, which use engine to drive the tools. The rated power and capacity of a battery pack for the electric power tools are also required to be increasing in order to achieve the working effect and duration similar to that of the engine tool.
When working and traveling outdoors, AC power supply is often needed to supply power for some equipment. Traditional portable power supply is usually supplied by internal cell group. Once the power of the cell group of the power supply is exhausted, AC power cannot be continuously provided.